Lazio, who had been leading the league since February, slipped up with a 1-1 draw away to Fiorentina and can now only hope for an unlikely turn of events on the final weekend of the season next week.
And that was not the worst of it, as far as Lazio were concerned. A Fiorentina fan was stabbed in the stomach and 20 others were injured in clashes after the match in Florence.
A day which started with police charges at Rome's main railway station, and continued with one carriage of a train carry Lazio fans being set alight, ended with further violence after the match.
Only 2,500 Lazio fans had been expected for the match at the Franchi stadium, but instead 7,000 turned up at the ground.
Next week Milan travel to face lowly Perugia, fighting relegation, while Lazio are at home to Uefa Cup and Italian Cup winners Parma, who will be looking to book their place in next season's Champions' League.
"It's a shame," said Lazio coach Sven Goran Eriksson. "Now we've got the European Cup-Winners' Cup final in England next Wednesday, so there's no time to dwell on things."
Gabriel Batistuta gave Fiorentina the lead with his 21st goal of the season. Lazio kept pushing forward and were rewarded when Yugoslav Sinisa Mijhailovic curled a long free-kick into the area and the unmarked Christian Vieri headed home. Fiorentina's Manuel Rui Costa had a penalty saved.
German striker Oliver Bierhoff, who has been struggling with his form all season, was on target with a hat-trick at the San Siro for Milan, taking his tally to 19. The Brazilian, Leonardo, scored the fourth.
The Milan coach, Alberto Zaccheroni, said: "Before, it depended on us and also what the other teams did. Now we're in the lead, it's exclusively down to us.
"We know that it's not going to be easy, because Perugia are in a difficult position in the table. We will be playing for everything, and so will they."
At the other end of the table the former Italian champions and Cup Winners' Cup holders Sampdoria were relegated from Serie A in cruel fashion yesterday, conceding a penalty two minutes into injury time and drawing 2-2 at Bologna.
Victory by Nantes' young side gave their club their first Cup triumph since 1979 when they also beat a Second Division side, Auxerre. Goalkeeper Mickael Landreau, 20 on the eve of the final, became the youngest captain to lift the trophy. Winger Olivier Monterrubio converted a penalty in the 57th minute following a foul on Frederic Da Rochas by Christophe Borbiconi.
Barcelona made a rare slip on their way to the Spanish title on Saturday as they were held 1-1 at home by Valladolid. The Catalans appeared set to go 12 points clear at the top as a stunning volley from Luis Enrique put them ahead on 62 minutes. But Valladolid fought back well, snatching a deserved equaliser with eight minutes to go as Harold Lozano rose above a flat-footed Barca defence to head past Ruud Hesp.
Barcelona, however, remain firm favourites for the championship after the 1-0 defeat for their closest rivals, Real Mallorca, on Friday.Reuse content